A motorcyclist suffered life-threatening injuries after an accident in Rochester. It happened Thursday night in the area of Lake Avenue and Denis Road around 9 p.m. Investigators say a dark vehicle cut off the motorcyclist, and the two vehicles collided. The dark vehicle reportedly left the scene. Police are looking for the driver. The motorcyclist, a 23-year-old man, suffered life-threatening injuries. Anyone with information is asked to call 911 or Crime Stoppers at 423-9300.